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Postexposure of Latent Electrostatic Images

IP.com Disclosure Number: IPCOM000095096D
Original Publication Date: 1965-Sep-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Shattuck, MD: AUTHOR [+2]

Abstract

In electrophotography, the electrostatic image consists normally of portions of low-charge density where the photoconductor surface has been exposed and of high-charge density where the surface has not been exposed to radiation. When an insufficient exposure has been given to the photoconductor, the charge density in the exposed area is sufficiently high to become apparent on toning and gives the copy an undesirable background. By postexposing the electrostatic image to the uniform radiation of a short duration, the charge density is lowered in the background without undue loss to the image density. This is because it is higher than necessary for good toning. The following are two examples employing the post-exposure step.

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Postexposure of Latent Electrostatic Images

In electrophotography, the electrostatic image consists normally of portions of low-charge density where the photoconductor surface has been exposed and of high-charge density where the surface has not been exposed to radiation. When an insufficient exposure has been given to the photoconductor, the charge density in the exposed area is sufficiently high to become apparent on toning and gives the copy an undesirable background. By postexposing the electrostatic image to the uniform radiation of a short duration, the charge density is lowered in the background without undue loss to the image density. This is because it is higher than necessary for good toning. The following are two examples employing the post-exposure step.

A coating of 1% of Malachite Green Oxalate and 4% 3, 5-dinitrobenzoic acid in polyvinylcarbazolc is charged with corona and then exposed through an image to a 25 watt tungsten lamp for 0. 01 seconds. The exposure is followed by a uniform exposure of 0.02 seconds to the same source and then toned. The quality of the image is comparable to that obtained by an exposure of 0. 02 seconds through the image with no postexposure.

The photoconductor in the example above is exposed through the image to the 25 watt tungsten lamp for 5 seconds. The layer is then charged with corona, given a postexposure of 0. 01 seconds to the same source and toned. The postexposure clears the background of the image without any...